Immunotoxicology of cigarette smoke condensates: Suppression of macrophage responsiveness to interferon γ

We have investigated systematically the effects of short-term exposure to main stream cigarette smoke condensates (CSC-MS) on basal and inducible functional capacities of murine peritoneal exudate macrophages. Macrophages treated with CSC-MS form granules that fluoresce orange under blue excitation, consistent with the speculation that they are polycyclic aromatic hydrocarbons (PAH). CSC-MS selectively suppressed interferon gamma (IFNγ) induction of four macrophage functional capacities: enhanced phagocytosis of immunoglobulin-opsonized sheep red blood cells, TPA-induced H₂O₂ production, class II major histocompatibility complex expression, and nitric oxide synthesis. In contrast, two macrophage functions that are not induced by IFNγ, basal electron transport and LPS-induced TNFα production, were enhanced by treatment with CSC-MS. These results suggest that the suppressive effects of CSC-MS on macrophage responsiveness were selective and were not due to nonspecific inhibition of general functions such as RNA or protein synthesis. Since macrophage responsiveness to IFNγ can result in induction of functional capacities that are fundamental to immunity, the data suggest that CSC-MS maybe deleterious to the general health of the smoker.